I need some advice on the best way to perform the following:

I need to keep up to date status of assets distributed across multi
sites. At the moment, sheets are emailed to a central location and
data is cut and pasted to (one of two) central data sheets, twice
daily.

Every month has a separate data sheet and the data must be pasted to
match its daily entry record.

Another sheet analyses all the data.

I would really appreciate any ideas on what would be the most
efficient way to get the daily data into the monthly data sheet.

I cannot automate forms like Outlook allows, nor can I use a central
directory on a server, or web access type solution for security
reasons.

The best option seems to be to email the daily sheet, rename it with
the date of the day it represents, then match the data to the correct
day and link it in somehow.

I tried to use the INDIRECT function but it requires the sheet to be
open. I can hard reference the data but it will mess up the automation
of the rest of the workbooks which automatically calculate days, dates
etc..

Any help appreciated.